Radio grid leak



Dec. 13,1932. F, o, PASCHALL 1,891,053

RADIO GRID LEAK Filed June l. 1927 Patented Dec. 13, 1932 gUNITED (STATES FREDERICK OLIVIER PASCHALL, OF BROOKLYN, YORK RADIO GRID Laax Application mediaan@ 1,1927. `seriai no. 195,725.

The invention relates to improvement in grid leaks in which a little block of anthracite coal is grounded on one side, by direct f ycontact while on the opposite side it has two 5 contacts, separated from each other by a Space of 1A; of an inch.

The device can be clipped into a standard 'grid condenser having clips,fand grounded. This arrangement provides a grounded lield lo of coal,'which acts as a suction for that portion of the signal which the tube cannot handle, thus allowing this unused portion to leak off gradually into the ground, which seems the logical place for it to iiow, thus taking this undesired leakage entirely out of the set, instead of merely setting it loose and leaving it to seek its own'outlet, which heretofore, has been into the coils, batteries and other kinstruments and whichk naturally interferes o with the good part of the signal and causes distortion on certainy dial settings.

The block ofcoal is ground smooth on all sides and measures about 5/8 inch long by 1% inch deep by 5%; inch' wide. The depth, how- 5 ever, will vary according to the capacity desired. This leakis to be used in the regular way, but its connections difer from other leaks in that it has a small hole in the centre of the top of the box through which a ground wire passes and connects to the ground plate, re- -ferred to as the thirdy contact member. The other two connections are at each end of the box and are the main ones, one connecting to the secondary winding'oii the detector coil (or tuner) and the other to the grid of the tube. To the accomplishment of the foregoing my invention consists of the elements and their relation one to the other, as'hereinafter particularly described and sought to be defined in the claims: reference being had to the accompanying drawing which shows the preferred embodiment of my invention, and

in which Fig. l is a cross-section view of the box, or

. housing, which is made of insulating material such as hard rubber, and shows the lower contact members, C., in place, with a space of about 1/8y of an inch separating them and a threaded machine bolt D. Fig. y2 holding each plate in place against eachgend of the box and extending beyond each end of the box about of an inch for connections and showingy a small'hole inthe top of the box through which the ground wire passes.

Fig. 2 shows the lower Contact members, made of brass, thin and pliable enough to conform to any slight unevenness on the Jface of the coal. These plates are each turned up y at right angles at one end and a small hole 50 placed in the turned up end for the contact bolt to pass through, the head of the bolt holding it on the inner side and a small nut v y screwed on the outside iirmly.

Fig. 8 shows the block of coal, ground 65 l smooth and flat on top and bottom and measuringabout 5/8 of aninch long by 5/8 of an inch wide and varying in thickness from about `1/S to 1,@ of an inch, accordingto capacity desired: the rthicker the coal is the higher the capacity in megohms. s f

Fig. 4: shows theupper contact member, known as the ground plate, made of smooth fiat brass about lg of an' inch thick and varyingin length and breadth so `as to work in conjunction with the varying thicknesses of coal in producing differentv values in megohms. The larger this plate is the lower will rbe the megohm value. n y

Thisground plate hasv a flexible wire, H, Fig. i soldered to the top, in centre, to which the ground connection is made. Fig. 5 shows a cross-section view of all the elements in place and under pressure of the spiral spring, which spring is coiled around '85 the ground wire H, in Fig. i and serves to hold all the members in engagement, the spring pressing iirmly against the top of the box. f

It wiil be further apparent that numerous changes and modiiications may be made in the structure disclosed without departing from the spirit of the invention defined in the following claims. n f

I claim :V n l. Agrid leak comprising an insulated box, a block of coal within the box, two lower Contact members and asingle upper Contact member engaging the coal, aspring located between the upper contact member'and the-100 box which serves to hold the coal and contacts into irm engagement, and terminal means connected to each of the Contact members.

Q. A grid leuk comprising an insulated box Containing a block of coal and two lower contact members and one upper Contact member, each member being held into firm engagement with the coal and with terminal means connected to each member.

3. A grid leak comprising a, piece of coal with two lower Contact members and one upper Contact member making firm engagement with the coal, the two lower members engaging the coal in d'erent places and all three Contact member having terminal means.

Intestmony whereof, I, F REDERIGK OLIVIER PASCHALL, have signed my name to this specification this 28th day of May 1927. FREDERICK OLIVIER PASCHALL. 

